import java.util.Scanner;

public class Day_33_2_客似云来 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        long[] fib = new long[81];
        fib[0] = 1;
        fib[1] = 1;
        for(int i = 2; i < 81; i++) {
            fib[i] = fib[i - 1] + fib[i - 2];
        }
        while(scan.hasNext()) {
            int from = scan.nextInt();
            int to = scan.nextInt();
            long sum = 0;
            for(int i = from - 1;i < to;i++) {
                sum += fib[i];
            }
            System.out.println(sum);
        }
    }
}
